The present invention relates to pharmaceutical compositions comprising water-soluble sulfonate-protected nanoparticles, more particularly, silver or gold nanoparticles. These compositions are useful in prevention or treatment of infections, conditions or disorders caused by microorganisms capable of binding to heparin sulfate, such as herpes simplex viruses.
Viruses pose significant global health challenges, while effective antiviral therapies continue to be hampered by the emergence of resistant viral strains and adverse side effects associated with prolonged use (Abdel-Haq N. et al., Indian. J. Pediatr., 2006, 73, 313-321; Baleux et al., Bioconjugate Chem., 2009, 20, 1497-1502; Enquist et al., J. Virol., 2009, 83, 5296-5308; Flexner et al., Nature Reviews Drug Discovery, 2007, 6, 959-966; each incorporated by reference herein in its entirety). Such obstacles have limited the extent of antiviral drugs in clinical use as compared with anti-bacterial drugs, and the development of safe and potent alternatives is needed. Multidisciplinary research efforts, integrated with classical epidemiology and clinical approaches, are therefore crucial for the development of alternative strategies towards improved antiviral drugs (Enquist et al., 2009)
Biological interactions are often multivalent in nature. Thus, recognition and cell signal transduction events often involve multiple copies of receptors and ligands that bind in a coordinated manner, resulting in drastically enhanced specificity, efficiency and strength of such interactions relative to their monovalent counterparts (Mammen et al., Angew. Chem. Int. Ed., 1998, 37, 2755-2794, incorporated by reference herein in its entirety). The attachment and entry of viruses into the host cells is an outcome of such multivalent interactions between viral surface components and cell membrane receptors (Mammen et al., 1998; Fields et al., in Fields' Virology, 5th Ed.; Wolters Kluwer Health/Lippincott Williams & Wilkins: Philadelphia, 2007; Flint et al., in Principles of Virology: Molecular Biology, Pathogenesis, and Control of Animal Viruses, 2nd Ed.; ASM Press: Washington, D.C., 2004; each incorporated by reference herein in its entirety). Interfering with these recognition events, and thereby blocking viral entry into the cells, is one of the most promising strategies being pursued to develop new antiviral drugs and preventive topical microbicides (Bowman et al., J. Am. Chem. Soc., 2008, 130, 6896-6897; Rusnati et al., Pharmacol. Ther., 2009, 123, 310-322; each incorporated by reference herein in its entirety).
The successful incorporation of functionalized nanomaterials in biomedical applications in recent years is derived from the combination of the inherent physical and chemical properties of nanomaterials with those of the surface bound ligands (Mrinmoy et al., Adv. Mater., 2008, 20, 4225-4241; Niemeyer, Angew. Chem. Int. Ed, 2001, 40, 4128-4158; Willner et al., FEBS Journal, 2007, 274, 302-309; each incorporated by reference herein in its entirety). As surface bound ligands, these biomolecules or their synthetic analogues are spatially directed, and render their carrier nanomaterials into multivalent biological effecter compounds (Hall et al., Antimicrob. Agents Chemother., 2008, 52, 2079-2088; Flavio Manea et al., Adv. Mater., 2008, 20, 4348-4352; Montet et al., J. Med. Chem., 2006, 49, 6087-6093; each incorporated by reference herein in its entirety). Such nano-biological constructs also generate an increased local concentration of the surface ligands over free unbound molecules and enhance ligand binding affinity to specific targets (Bowman et al., 2008; Bastus et al., ACS Nano, 2009, 3, 1335-1344; Lytton-Jean et al., J. Am. Chem. Soc., 2005, 127, 12754-12755; Ma et al., ACS Nano, 2009, 3, 2686-2696; each incorporated by reference herein in its entirety). Indeed, this approach has previously been used to develop nanoparticle-based targeted drug carriers (Wang et al., ACS Nano, 2009, 3, 3165-3174; incorporated by reference herein in its entirety), rapid pathogen detection (Phillips et al., Angew. Chem. Int. Ed, 2008, 47, 2590-2594; incorporated by reference herein in its entirety), biomolecular sensing (Nam et al., J. Am. Chem. Soc., 2004, 126, 5932-5933; Stoeva et al., J. Am. Chem. Soc., 2006, 128, 8378-8379; each incorporated by reference herein in its entirety), as well as nanoparticle-based cancer therapies (Rozhkova et al., Nano Lett., 2009, 9, 3337-3342; incorporated by reference herein in its entirety). The use of functionalized nanoparticles can be extended to the development of antiviral drugs that act by interfering with viral infection, in particular during attachment and entry. The efficacy of the antiviral multivalent nanoparticles approach has been recently illustrated with the demonstration that mercaptobenzoic acid modified gold nanoparticles convert a weakly binding small molecule into a multivalent conjugate that efficiently inhibits HIV-1 infection (Bowman et al., 2008). Based on similar principles, glycol-functionalized nanoparticles have recently been used for optical detection of viruses (Niikura et al., Bioconjugate Chem., 2009, 20, 1848-1852; incorporated by reference herein in its entirety).
Herpes simplex virus (HSV)-associated diseases are among the most widespread infections, affecting about 60-95% of human adults. These diseases are incurable and persist during the lifetime of the host, often in latent form. The clinical manifestations of such infections are variable and influenced by the portal of viral entry, age of the host, degree of host immunocompetence, primary or secondary nature of the disease and other unknown factors. Clinical presentations of HSV infection range from asymptomatic infection to mucocutaneous conditions such as labial herpes, also known as fever blisters or cold sores, keratitis and genital herpes, as well as central nervous system complications such as neonatal herpes and herpetic encephalitis that could have fatal outcome. Recurrent mucocutaneous disease episodes appear in 15-40% of HSV-infected individuals. Of note, genital herpes is currently considered one of the most prevalent sexually transmitted infections worldwide.
Current management approach to HSV infection does not target viral eradication, but rather the prevention of transmission, suppression of recurrence, attenuation of clinical course and complications, as well as promotion of healing. Topical, oral, or intravenous Acyclovir and other nucleoside derivatives have been approved for treatment of HSV infections and are widely used. However, the emergence of resistant viral strains, mainly after prolonged treatment in immunocompromised patients, is one of the main reasons for continuous search of new anti-herpes drugs that can inhibit infection by both wild-type viruses and drug-resistant strains.
Glycoprotein C (gC) mediates high affinity attachment of the HSV-1 to cells by binding to glycosaminoglycans (GAGs) of heparan sulfate (HS) or to chondroitin sulfate on the cell surface. The significance of this interaction is highlighted by the reduced HSV-1 infection in the absence of either viral gC or cell surface heparan sulfate (Arvin et al., in Human Herpesviruses: Biology, Therapy, and Immunoprophylaxis, Cambridge: New York, 2007; Mardberg et al., J. Gen. Virol., 2001, 82, 1941-1950; Reske et al., Rev. Med. Virol., 2007, 17, 205-215; each incorporated by reference herein in its entirety).
Many pathogenic microorganisms, like HSV, express on their surface proteins that are capable of binding to heparan sulfate, and these interactions appear important for their infectivity. Compounds that mimic heparan sulfate chains, such as the sulfated polysaccharide heparin, were shown to inhibit HSV attachment to cells, suggesting that these compounds act via competition with heparan sulfate chains for binding to the virus attachment proteins. Interference with some post-attachment steps in HSV infection by these compounds has also been suggested.
Previously, sulfated and sulfonated polysaccharides, as well as several other polyanionic compounds including dendrimers, have been investigated as potential anti-HSV-1 agents based on the principle that they mimic heparan sulfate and compete for the binding of the virus to the cell. These candidate microbicides act by blocking cell surface receptors-virus interactions, thereby inhibiting virus attachment/entry, and possibly blocking cell-to-cell spread as well (Rusnati et al., 2009; Gong et al., Antiviral Res., 2002, 55, 319-329; Gong et al., Antiviral Res., 2005, 68, 139-146; Herold et al., J. Virology, 2002, 11236-11244; each incorporated by reference herein in its entirety). Nanoparticle-bound ligands have potentially enhanced affinity to interact with target molecules, due to their spatial orientation and large surface area.
Zou et al. (J. Colloid Interface Sci., 2006, 295, 401-408; incorporated by reference herein in its entirety) discloses a one-phase method for the synthesis of mercaptoethane sulfonate-protected, water-soluble gold and silver nanoparticles (Au-MES NPs and Ag-MES NPs). As described, both Au-MES NPs and Ag-MES NPs are soluble in water up to 2.0 mg/ml and the stability of Au-MES NPs is much better than that of Ag-MES NPs. When dissolved in water, they behave like a polyanion and can be used to build multilayer films with polyaniline (PANI) by way of layer-by-layer.
US 2010/056485 (incorporated by reference herein in its entirety) discloses a silver nanoparticles-based antimicrobial composition, comprising an amphiphilic molecule having at least one hydrophilic group, e.g., carboxylate, sulfonate, sulfate, sulfinate, phosphate, phosphinate, phosphonate, and quaternary amine, and at least one hydrophobic group attached thereto, wherein at least one silver nanoparticle is in contact with the amphiphilic molecule. As stated in this publication, the antimicrobial properties of this composition derive from the silver nanoparticles.